The present invention relates to a displaying apparatus for use in construction machines with a blade having a level sensor disposed above the blade for detecting laser beams serving as a datum by means of the level sensor and displaying the information based on the detected datum on a remote display.
In civil engineering work such as creating land by leveling the ground, construction (engineering) machinery with a blade such as bulldozers and crawlers are used.
In the past, the operator of the construction machine, while proceeding with such ground leveling work by eye measure, frequently made surveys to check the levelness of the land in the course of the work.
Recently, however, by the use of a rotating laser device, it has become possible for the operator of a construction machine to directly check the levelness while sitting in the operator's seat. Namely, laser beams serving as a datum plane are detected by a level sensor provided above the blade and the direction of a deviation of the ground from the datum plane is displayed on a display.
In order that the laser beams are not screened by the body of the construction machine or the like, such a level sensor is placed by means of a pole at a relatively high position above the blade. Therefore, especially when the construction machine is large, the level sensor is kept apart from the operator (for example, 5 m) and the display becomes difficult to see.
In such a case, a remote display is provided close to the operator's seat so that it becomes easier for the operator to read the content of the display.
It has so far been practiced to connect the remote display and the level sensor by a cable or by radio.
When a display and a level sensor are connected by a cable, the cable is strung between the body of the construction machine and the blade. Since the blade violently moves and suffers a severe shock during the land creating work, sometimes interference is produced on the cable or the cable itself gets in the way of the moving blade.
Laying the cable free from such an interference and falling off requires a certain time and labor and it costs accordingly.
On the other hand, when communication is held by a radio wave, since the radio wave has no directionality, such a thing sometimes occurs, when a plurality of construction machines work at spots in close vicinity, that the remote display is disturbed by a radio wave from a level sensor not of its own and causes a malfunction.
To prevent such a malfunction from occurring, it will be effective to previously adjust the frequency for each pair of the level sensor and the remote display. However, making such initial adjustments is troublesome.